Medium for recording audio signal, recorder and player

ABSTRACT

A recording medium for a disc having a first recording region in which a first portion of audio signals supplied is recorded and a second recording region in which a second portion of audio signals supplied is recorded. The first and second portions of the audio signals recorded in the first and second recording regions are synthesized and reproduced or selected and reproduced to realize variegated audio reproduction.

TECHNICAL FIELD

This invention relates to a recording medium, a recording apparatus forthe recording medium, a reproducing apparatus for the recording medium,a recording method for audio signals and a reproducing method for audiosignals. More particularly, it relates to a recording medium on which torecord audio signals, a recording apparatus for the recording medium, areproducing apparatus for the recording medium, a recording method foraudio signals and to a reproducing method for audio signals.

BACKGROUND ART

On a compact disc, referred to below simply as CD, which is astandardized optical disc with a diameter of 12 cm, there are recordedaudio signals, as digital data converted from analog audio signals.

On a routine CD, there is recorded a musical number as a set of audiodata making up the musical number. For example, if a musical number ismade up of a lyric and the accompaniment music for this lyric, the lyricand the accompaniment music are recorded as one as a set of audio data.

In an orchestra performed by plural sorts of musical instruments, theperformance by the plural sorts of musical instruments is recorded asone as a set of audio data.

In a disc on which the lyric and the accompaniment music therefor havebeen recorded as one as a set of audio data, it is not possible toselect and reproduce only the lyric or the accompaniment music, suchthat, when only the accompaniment music of a musical number is to bereproduced, the accompaniment music needs to be recorded independentlyof audio data containing the lyric and the accompaniment music.

Even in case of a disc having recorded thereon as one the performance bythe plural sorts of musical instruments as a set of audio data, it isnot possible to reproduce the performance by only a certain musicalinstrument forming an orchestra, such as a piano.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to provide arecording medium whereby it is possible not only to reproduce a musicalnumber made up of a lyric and the accompaniment music or the orchestraperformed by plural sorts of musical instruments as a set of audiosignals, but also to reproduce only the accompaniment music of a musicalnumber made up of the lyric and the accompaniment music or only theperformance by certain musical instrument(s) of the orchestra.

It is another object of the present invention to provide a recordingmethod and apparatus whereby it is possible to record readily the audiosignals recorded on a recording medium which enables recording of a setof audio signals in their entirety or only a portion of the lyric or theaccompaniment music of the set of audio signals.

It is yet another object of the present invention to provide areproducing method and apparatus whereby it is possible to select andreproduce readily the audio signals recorded on a recording medium whichenables recording of a set of audio signals in their entirety or only aportion of the lyric or the accompaniment music of the set of audiosignals.

A recording medium proposed for accomplishing the above objects,according to the present invention, at least includes a first recordingregion for recording a first portion of supplied audio signals, and asecond recording region for recording a second portion of supplied audiosignals. The first and second portions of the audio signals, recorded onthe first and second recording regions, respectively, are synthesizedand reproduced or selected and reproduced.

The recording medium according to the present invention includes nrecording regions in which sampled data generated on sampling audiosignals from a sound source with a sampling frequency of 44.1 kHz arerecorded from one of n partial portions to another, with each partialportion being recorded in each recording region.

According to the present invention, in reproducing audio signals from arecording medium on which audio signals from a sound source are sampledby a pre-set sampling frequency to generate sampled data which sampleddata are separated into n partial portions, at least one of which is theentire sampled data, signals are read out from the n recording regionsof the recording medium, and the read-out signals of the respectiverecording regions of the n recording regions of the recording medium areselectively reproduced. Alternatively, the data recorded in at least twoof the entire recording regions are synthesized and reproduced.

Moreover, according to the present invention, in reproducing a recordingmedium having a first recording region in which a first portion of audiosignals supplied is recorded and a second recording region in which asecond portion of audio signals supplied is recorded, there beingrecorded on the recording medium a discrimination signal indicatingwhether the first and second portions are to be output on addition or onsubstation, the first portion read out from the first recording regionand the second portion read out from the second recording region isreproduced based on the contents of the discrimination signal read outfrom the recording medium.

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description of thepresent invention and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing an embodiment of an opticaldisc embodying the present invention.

FIG. 2 illustrates two optical pickups adapted for recording audiosignals on first and second recording layers of an optical disc.

FIG. 3 is a block diagram showing an embodiment of a recording apparatusand an embodiment of a reproducing apparatus according to the presentinvention.

FIG. 4 is a cross-sectional view showing the state of recording audiosignals on first and second recording layers of an optical discaccording to the present invention and the state of reproducing therecorded audio signals.

FIG. 5 is a block diagram showing a modification of a reproducingapparatus according to the present invention.

FIG. 6A to FIG. 6C show switching timing in reproducing the audiosignals recorded on plural recording layers on the optical disc by areproducing apparatus shown in FIG. 5.

FIG. 7 is a block diagram showing a modification of a recordingapparatus according to the present invention.

FIG. 8 shows a modification of an optical disc according to the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to the drawings, a recording medium, a recording apparatus anda reproducing apparatus according to the present invention will beexplained in detail.

A recording medium according to the present invention is comprised of anoptical disc 1, which is provided with a substrate 2 of alight-transmitting synthetic resin, such as polycarbonate resin, orglass, as shown in FIG. 1. On one surface of the substrate 2, there isprovided a pit pattern 3 which is a pattern of micro-sized crests andgrooves corresponding to recorded audio data. If the substrate 2 ismolded from synthetic resin, this pit pattern 3 is formed simultaneouslywith the molding of the substrate 2 by a stamper mounted on an injectionmolding system in injection molding the substrate 2. If the substrate 2is formed of glass, it is molded using a 2P (PhotoPolymerization)method. In this 2P method, a photo-curable resin, such as UV lightcurable resin, is charged between a glass substrate and a stamper, andthe light, such as UV light is illuminated from the side glass substrateto cure the pattern of the crests and grooves of the stamper in order totranscribe the pattern of the crests and grooves of the stamper to thelayer of the photo-curable resin.

The substrate 2, used in this optical disc 1, is obtained on injectionmolding a polycarbonate resin. On one surface of the substrate 2 isformed audio data as pit pattern 3. Similarly to the substrate of theso-called routine Compact Disc (CD), the substrate 2 is of a diameter of12 cm and a thickness of approximately 1.2 mm.

On one surface of the substrate 2, carrying the pit pattern 3, there isformed a first recording layer 4 for overlying the pit pattern 3, asshown in FIG. 1. This first recording layer 4 is formed as asemi-transparent film for transmitting a pre-set portion of a light beamradiated from the side substrate and for reflecting a pre-set portionthereof, and is formed as a film of silicon-based material, such asSi₃N₄ and SiO₂ to a thickness of 100 to 500 nm. The first recordinglayer 4 is formed as a multi-layer of Si₃N₄ and SiO₂. The layers ofSi₃N₄ and SiO₂, making up the first recording layer 4, are formed on onesurface of the substrate 2 by vacuum deposition or sputtering.

On the first recording layer 4 is formed a second recording layer 6 viaan intermediate layer 5 formed e.g., of a light-transmitting UV lightcurable resin. The intermediate layer 5 is formed to a pre-set thicknessbecause the intermediate layer 5 performs the role of opticallyseparating the first recording layer 4 and the second recording layer 6from each other so that these recording layers 4, 6 will not bepositioned within the depth of focus of an objective lens which isadapted for converging the light beam to these recording layers 4, 6 toilluminate the recording layers. Specifically, the intermediate layer 5is formed to a thickness on the order of 30 μm. The intermediate layer5, if too thin in thickness, is unable to separate the reflected lightfrom the first recording layer 4 sufficiently from the reflected lightfrom the recording layer 6, to render it difficult to detect thereflected light beams sufficiently. If conversely the intermediate layer5 is too thin, spherical aberration, for example, is produced by theintermediate layer 5. Accordingly, the intermediate layer 5 is set to anappropriate thickness taking these points into consideration.

It is noted that the intermediate layer 5 is formed by coating a UVlight curable resin on the first recording layer 4 by a spin coatingmethod and subsequently illuminating the UV light for curing.Alternatively, the intermediate layer 5 may be formed on depositing theUV light curable resin layers, each being of a thickness of 5 to 10 μm,a plurality of numbers of times. Still alternatively, the intermediatelayer 5 may be formed by bonding a transparent sheet on the firstrecording layer 4.

On one surface of the intermediate layer 5 is formed a pit pattern 7,which is a pattern of micro-sized crests and grooves corresponding toaudio data. This pit pattern 7 may also be formed by the above-mentioned2P method which is used in forming a pit pattern on a glass substrateusing the photo-curable resin, as described above.

The second recording layer 6 is formed to overlie the pit pattern 7formed on one surface of the intermediate layer 5 in superposition onthe first recording layer 4. The second recording layer 6 is formed of amaterial exhibiting high reflectance, such as aluminum (Al), gold (Au)or silver (Ag) on the intermediate layer 5 with the pit pattern 7, inorder to reflect the light beam transmitted through the first recordinglayer 4 and radiated therefrom with high efficiency onto an opticalpickup mounted facing the substrate 2 to output a light beam. On thesecond recording layer 6 is formed a protective layer 8 formed e.g., ofa UV light curable resin to protect the second recording layer 6. Thisprotective layer 8 is formed by coating a UV light curable resin on thesecond recording layer 6 by a spin coating method and illuminating theUV light thereon to cure the UV light curable resin.

On this first recording layer 4, there are recorded audio datacorresponding to the accompaniment music separated from a completemusical number composed of the lyric and the accompaniment music of thislyric, as partial audio data, whereas, on the second recording layer 6,there are recorded audio data corresponding to the entire completemusical number composed of the lyric and the accompaniment music of thislyric.

The audio data may be recorded in various configurations on the firstand second recording layers 4, 6. For example, the audio datacorresponding to the accompaniment music separated from the completemusical number composed of the lyric and the accompaniment music may berecorded as partial audio data on the first recording layer 4, with theaudio data corresponding to the lyric being also recorded on the secondrecording layer 6 as partial audio data.

In the case of a musical number, such as orchestra performed by pluralsorts of musical instruments, audio data portions corresponding to theaudio data performed by a piano of the orchestra may be recorded aspartial audio data. On the other hand, the first recording layer 4, withthe entire audio data comprised of the complete orchestra, being thenrecorded on the second recording layer 6 as partial audio data.

The respective audio data, recorded as respective partial audio dataportions of the complete musical number, on the first and secondrecording layers 4, 6, are recorded as lyric or its accompaniment music,the audio data as self-contained pieces of the musical number, eachforming a musical number set, so that, even if only one of the first andsecond recording layers 4, 6 is reproduced, self-contained audio data,as a portion of the musical number, is reproduced.

The audio data, recorded on the first and second recording layers 4, 6,are generated by sampling at a sampling frequency of 44.1 kHz followedby 16-bit quantization of analog audio signals supplied from a signalsource for recording on the respective recording layers.

The audio data, recorded on the first and second recording layers 4, 6,are recorded thereon to be reproduced by a disc reproducing deviceemploying an light beam having a wavelength of approximately 780 nm.

On one or both of the first and second recording layers 4, 6 of theoptical disc 1 are recorded discrimination data for discriminating thecombination of the partial audio data recorded on the first and/orsecond recording layers 4, 6. If audio data corresponding to theaccompaniment music, separated from the complete musical number composedof the lyric and the accompaniment music for this lyric, is recorded aspartial audio data, the discrimination data is data indicating theaddition of the partial audio data recorded on the first and secondrecording layers 4, 6, whereas, if the entire music composed of thelyric and the accompaniment music for this lyric is recorded on thefirst recording layer 4 as partial audio data and the audio datacorresponding to the lyric is recorded as partial audio data, thediscrimination data is data indicating the subtraction the partial audiodata recorded on the second recording layer 6 from the partial audiodata recorded on the first recording layer 4. This discrimination datais recorded on e.g., a recording area, carrying e.g., management orarchival data, of one of the first and second recording layers 4, 6which is read out first next to the loading of the optical disc 1 on thereproducing apparatus.

A recording apparatus for recording audio data on the optical disc 1, onwhich there are recorded different portions separated from a completemusical number, as respective audio data portions, or audio datacorresponding to the entire musical number and a potion of the musicalnumber, as respective audio data portions, and a reproducing apparatusfor reproducing the optical disc recorded by this recording apparatus,are hereinafter explained.

First, a recording apparatus 12 for recording audio data on the opticaldisc 1, according to the present invention, is explained.

Referring to FIG. 2, the recording apparatus 12 of the present inventionincludes two optical pickups, having a first objective lens 9 and asecond objective lens 10. A recording light beam L₁, converged by thefirst objective lens 9, is focussed on the first recording layer, and arecording light beam L₂, converged by the second objective lens 10, isfocussed on the second recording layer 6 for recording audio data on thefirst and second recording layers 4, 6.

Referring to FIG. 3, the recording apparatus 12 according to the presentinvention includes a first input terminal 13, fed with audio signals,recorded on the first recording layer 4, and a second input terminal113, fed with audio signals recorded on the second recording layer 6.

In the complete musical number composed of the lyric and theaccompaniment music for this lyric, signals for the accompaniment musicare separated and audio signals corresponding to this accompanimentmusic are fed as partial audio data to the first input terminal 13. Onthe other hand, signals corresponding to the lyric of the musical numberare separated so that audio signals corresponding to this lyric are fedto the second input terminal 113. That is, in the recording apparatus 12according to the present invention, the signals corresponding to thelyric and the signals corresponding to the accompaniment music areseparated from the complete musical number, made up of the lyric and theaccompaniment music, from a reproducing apparatus, not shown, operatingas a sound source for reproducing e.g., a master tape having recordedthereon the original sound. The audio signals of the lyric and those ofthe accompaniment music, thus separated, are fed to the first and secondinput terminals 13, 113, respectively. Alternatively, the audio signalsproduced on reproducing a master tape, having separately orindependently recorded thereon the lyric and the accompaniment music,making up a complete musical number, are input to the first and secondinput terminals 13, 113, respectively.

Meanwhile, the audio signals input to the first and second inputterminals 13, 113 are left channel audio data and right channel audiodata in order to permit stereophonic reproduction.

The analog audio data, input to the first and second input terminals 13,113, and which correspond to the lyric portion and to the accompanimentmusic portion, respectively, are routed to first and second A/Dconverters 14, 114 where the signals are sampled at the samplingfrequency of 44.1 kHz accepted by these A/D converters 14, 114, andquantized in 16 bit stereophonic two-channel audio signals, to be outputfrom the A/D converters 14, 114.

The digital audio signals, output from the first D/A converter 14, aresequentially routed to a first error correction coding circuit 16, afirst modulation circuit 17 and a first bi-level circuit 18, making up asignal processing system responsible for recording on the firstrecording layer 4.

Similarly, the digital audio signals, output from the A/D converter 114,are sequentially routed to a second error correction coding circuit 116,a second modulation circuit 117 and a second bi-level circuit 118,making up a signal processing system responsible for recording on thesecond recording layer 6.

The first and second error correction coding circuits 16, 116 encodesamples with the combination of the cross-interleaving and four-orderReed-Solomon code, using an algorithm of the cross interleaveReed-Solomon code (CIRC). The first and second modulation circuits 17,117 modulate encoded outputs of the first and second error correctioncoding circuits 16, 116 in accordance with the algorithm of EFM (eightto fourteen modulation). The first and second bi-level circuits 18, 118convert modulated outputs of the first and second modulation circuits17, 117 into bi-level data for recording on the first and secondrecording layers 4, 6 of the optical disc 1, respectively.

The data fed from the first input terminal 13 and converted intobi-level data by the above-described signal processing system, that isrecording data output by the bi-level circuit 18, are recorded by thefirst optical pickup having the first objective lens 9 shown in FIG. 2on the first recording layer 4. The recording data fed from the secondinput terminal 113 and converted by the above-described signalprocessing system into bi-level data, that is recording data output bythe bi-level circuit 118, are recorded on the second recording layer 6by the second optical pickup having the second objective lens 10 shownin FIG. 2.

A reproducing apparatus for reproducing the optical disc 1, havingrecorded in its first recording layer 4 signals of a lyric portion of acomplete musical number composed of the lyric portion and theaccompaniment music for the lyric portion, and also having recorded inits second recording layer 6 signals of the accompaniment music portion,is now explained.

Referring to FIG. 2, this reproducing apparatus 20 includes two opticalpickups, one of which has the first objective lens 9 and the other ofwhich has the second objective lens 10. The recording light beam,converged by the first objective lens 9, is focussed on the firstrecording layer 4, the recording light beam, converged by the secondobjective lens 10, is focussed on the second recording layer 6 and thereturn light beam reflected from the first and second recording layers4, 6 are detected to reproduce the audio data recorded on the first andsecond recording layers 4, 6. It is of course possible to use a soleoptical pickup and to switch the focussing position of the light beamilluminated from the objective lens on the optical disc 1 from the firstrecording layer 4 to the second recording layer 6 and vice versa.

In the reproducing apparatus 20, signals read out by the first opticalpickup from the first recording layer 4 of the optical disc 1rotationally driven at e.g., CLV by a rotational driving unit, notshown, are sequentially routed to a first RF circuit 21, a firstdemodulating circuit 22 and to a second error correction circuit 23,making up a playback signal processing unit. The first RF circuit 21performs RF processing, such as amplification, on the signals read outfrom the first optical pickup, to generate RF signals, which are routedto the first demodulating circuit 22. The first demodulating circuit 22performs EFM demodulation on the RF signals to route the demodulatedsignals to the first error correction circuit 23. The first errorcorrection circuit 23 corrects the demodulated output data from thefirst demodulating circuit 22 by CIRC to route the resulting data to afirst error interpolation circuit 24. The first error interpolationcircuit 24 interpolates the corrected output data from the correctioncircuit 23.

Similarly to the signals read out by the first optical pickup from thefirst recording layer 4, the signals read out by the second opticalpickup from the second recording layer 6 of the optical disc 1 aresequentially routed to a second RF circuit 121, a second demodulatingcircuit 122 and to a second error correction circuit 123. The second RFcircuit 121 performs RF processing, such as amplification, on thesignals read out from the second optical pickup, to generate RF signals,which are routed to the second demodulating circuit 122. The seconddemodulating circuit 122 performs EFM demodulation on the RF signalsfrom the second RF circuit 121 to route the demodulated signals to thesecond error correction circuit 123. The second error correction circuit123 corrects the demodulated output data from the demodulating circuit122 by CIRC to route the resulting data to a second error interpolationcircuit 124. The second error interpolation circuit 124 interpolates thecorrected output data from the correction circuit 123.

Meanwhile, the reproducing apparatus 20 includes a playback modeselection button, not shown. This playback mode selection button selectsthe playback mode of audio data recorded on the optical disc 1.

On output sides of the first and second error interpolation circuits 24,124, there are provided first and second data output selection circuits25, 125 for selecting the outputting of audio data read out from thefirst and second recording layers 4, 6 by selecting a playback modeselection button, not shown.

If a playback mode selection button, not shown, is acted on by a user,and a playback mode according to the discrimination data pre-recorded onthe optical disc 1, the audio data read out from the first and secondrecording layers 4, 6 are routed to the multiplexer 26 through the firstand second data output selection circuits 25, 125. The multiplexer 26,fed with the audio data read out from the first and second recordinglayers 4, 6, sums or subtracts the audio data read out from the firstrecording layer 4 and the audio data read out from the second recordinglayer 6 to output the resulting data.

For example, if, when audio data corresponding to accompaniment music,separated from the complete musical number comprised of a lyric and theaccompaniment music for this lyric, is recorded on the first recordinglayer 4, as partial audio data, and audio data corresponding to thelyric is recorded as partial audio data in the second recording layer 6,discrimination data is recorded as data indicating summation of audiodata read out from the first and second recording layers 4, 6, themultiplexer 26 sums the audio data read out from the first and secondrecording layers 4, 6 to output the summation data. this summation datais audio data of the complete musical number containing audio datacorresponding to the accompaniment music recorded on the first recordinglayer 4 and also containing audio data corresponding to the lyricrecorded on the second recording layer 6.

If, when audio data corresponding to the entire complete musical numbercomprised of a lyric and the accompaniment music for this lyric, isrecorded on the first recording layer 4, as partial audio data, andaudio data corresponding to the lyric is recorded as partial audio datain the second recording layer 6, discrimination data is recorded as dataindicating subtraction of the partial audio data recorded on the secondrecording layer 6 from the audio data read out from the first recordinglayer 4, the multiplexer 26 subtracts the audio data read out from thesecond recording layer 6 from the audio data read out from the firstrecording layer 4 to output the resulting subtraction data. Thissummation data is audio data containing only audio data corresponding tothe accompaniment music of the lyric.

The audio data, summed or subtracted by the multiplexer 26, is routed toa first low-pass filter (LPF) 27. The first LPF 27 applies filtering toaudio data output from a multiplexer 26 with approximately 20 kHz as acut-off frequency. The audio data, filtered by the first LPF 27, isrouted to a first D/A converter 28 for conversion to analog audiosignals which are output from the first output terminal 29. Byconnecting a reproducing apparatus having an electro-acoustictransducer, such as a loudspeaker or a headphone, to the first outputterminal 29, there is produced acoustic reproduction by the audio soundcorresponding to the sum of the audio data read out from the firstrecording layer 4 and audio data read out from the second recordinglayer 6, or acoustic reproduction by the audio sound corresponding tothe audio data read out from the first recording layer 4 less the audiodata read out from the second recording layer 6.

If a playback mode selection button, not shown, is acted on by the user,such that the playback mode for independently outputting audio data readout from the first and second recording layers 4, 6 of the optical disc1 is selected, the audio data read out from the first and secondrecording layers 4, 6 is sent via first and second data output selectioncircuits 25, 125 to second and third LPFs 27 a, 27 b. These second andthird LPFs 27 a, 27 b apply filtering, with approximately 20 kHz as acut-off frequency, to the audio data output by the first and second dataoutput selection circuits 25, 125. The audio data, filtered by thesecond and third LPFs 27 a, 27 b, are routed to second and third D/Aconverters 28 a, 28 b, for conversion into analog audio signals, whichare output from second and third output terminals 29 a, 29 b,respectively. By connecting a reproducing apparatus, such as aloudspeaker or a headphone, provided with an electro-acoustictransducer, acoustic reproduction takes place by the audio sound basedon audio data read out from the first and second recording layers 4, 6.By selecting signals output by the second and third output terminals 29a, 29 b, audio data recorded on the first and second recording layers 4,6 can be selectively reproduced and heard by the user.

By recording plural partial audio data of the complete musical number,or a partial audio data and the entire audio data, in the first andsecond recording layers 4, 6 provided on the optical disc 1, and bysumming or subtracting the audio data read out from the recording layers4, 6, it is possible to realize diversified acoustic reproduction.

It is noted that, since the audio data are recorded on the first andsecond recording layers 4, 6 of the optical disc 1 as meaningful audiodata from one partial audio data recorded on the recording layer 4 or 6to another, acoustic reproduction similar to that realizedconventionally can be achieved by reproducing audio data recorded onlyon the recording layer 4 or 6 by a reproducing apparatus provided with asole optical pickup having a sole objective lens.

Referring to FIGS. 4 and 5, another embodiment of a reproducingapparatus for reproducing an optical disc 1, having plural partial audiodata of a complete musical number or the entire musical number andpartial audio data thereof, recorded on the first and second recordinglayers 4, 6, is explained with reference to FIGS. 4 and 5.

This reproducing apparatus 30 includes a readout mechanism, having anoptical pickup 31 and a signal readout unit 32 for reading out audiodata recorded on the first and second recording layers 4, 6 of theoptical disc 1, a first buffer memory 33 for memorizing playback datacorresponding to the audio data recorded on the first recording layer 4and reproduced with modulation and error correction processing by thesignal readout unit 32, and a second buffer memory 34 for memorizingplayback data corresponding to the audio data recorded on the secondrecording layer 6 and reproduced with modulation and error correctionprocessing by the signal readout unit 32. The reproducing apparatus 30also includes a multiplexer 35 for summing or subtracting outputs readout from the first and second buffer memories 33, 34 and a servo circuit38 for causing movement of the objective lens of the optical pickup 31in a direction parallel and/or perpendicular to the optical axis of theobjective lens to control the light beam radiated from the opticalpickup 1 to scan the target recording track of the optical disc 1. Theservo circuit 38 is also provided with a switching unit 39 for switchingthe light beam radiated from the optical pickup 31 and converged by theobjective lens 11 so that the light beam will be selectively focussed onone of the first and second recording layers 4, 6. The reproducingapparatus 30 also includes a spindle motor 40 for rotationally drivingthe optical disc 1 at a CLV or CAV under control by the servo circuit38.

The reproducing apparatus 30 includes a CPU (central processing unit) 37for deciding whether the audio data recorded on the first and secondrecording layers 4, 6 of the optical disc 1 are to be reproduced, theaudio data recorded on the first and second recording layers 4, 6 are tobe synthesized and reproduced, or a conventional optical disc, such asCD, is to be reproduced, under a command from a user or depending on theconfiguration of the disc to be loaded, and for controlling the servocircuit 38, switching unit 39, signal readout unit 32 and a buffermanagement unit 36 depending on the results of decision. To the CPU 37is connected an operating unit, not shown, provided with a playback modeselection button for the user to select the playback mode of the opticaldisc 1.

Meanwhile, in the present reproducing apparatus 30, the audio data readout from the first and second recording layers 4, 6 may be stored indifferent memory storage areas of a common buffer memory 34 withoutemploying the two buffer memories, namely the first and second buffermemories 33, 34.

In the reproducing apparatus 30, the audio data read out from the firstand/or second recording layers 4, 6 of the optical disc 1 are routed tothe signal readout unit 32. Based on control signals from the servocircuit 38 and the switching unit 39, the optical pickup 31 iscontrolled to focus a light beam selectively on the first recordinglayer 4 or on the second recording layer 6 to scan the first or secondrecording layer 4, 6.

The signal readout unit 32, making up a readout mechanism along with theoptical pickup 31, performs pre-set RF processing, such asamplification, or replay signal processing, such as demodulation anderror correction processing, on the output signal of the optical pickup31, that is the signal derived from the audio data read out from thefirst or second recording layer 4, 6, to route the processed signal tothe first buffer memory 33 or the second buffer memory 34.

The first buffer memory 33 is a memory for writing or reproducing replaydata corresponding to audio data recorded on or read out from the firstrecording layer 4 or reproducing the replay data, and the second buffermemory 34 is a memory for writing replay data corresponding to audiodata recorded on or read out from the second recording layer 6. Datawriting or readout on or from the first buffer memory 33 or the secondbuffer memory 34 is controlled by the buffer management unit 36.

The operation of the reproducing apparatus 30 shown in FIG. 5 is nowexplained in detail.

If the user acts on the a playback mode selection button, not shown,provided on the reproducing apparatus, and the command is to reproduceonly the audio data recorded on the first recording layer 4 of theoptical disc 1, the CPU 37 selects reproduction of audio data only fromthe first recording layer 4, so that the optical pickup 31 is controlledby the servo circuit 38 and the switching unit 39 to focus the lightbeam on the first recording layer 4 of the optical disc 1, run inrotation by the spindle motor 40, to scan only the first recording layer4 of the optical disc 1. If the optical pickup 31 is controlled to scanthe first recording layer 4, the return light beam reflected back onlyfrom the first recording layer 4 is detected by a photo detector of theoptical pickup 31, so that an output signal of the optical pickup 31 issent to the signal readout unit 32 to read out only audio data recordedon the first recording layer 4. The output data derived from the audiodata recorded on the first recording layer 4 and which is output by thesignal readout unit 32 is subjected to pre-set replay processing, suchas demodulation and error correction, so as to be written in the firstbuffer memory 33 at a pre-set timing under control by the buffermanagement unit 36. The data then is read out from the first buffermemory 33 so as to be output from an output terminal 41 via amultiplexer 35.

The audio data, read out from the first recording layer 4, is convertedby an error interpolation unit 25, an LPF 26 and a D/A converter 27,similar to those used in the respective apparatus 20 shown in FIG. 3, soas to be output at the output terminal 41.

If a replay mode selection button, not shown, provided on thereproducing apparatus 30, is acted on by the user, such that the replaymode of reproducing only audio data recorded on the second recordinglayer 6 of the optical disc 1 is selected, the processing similar tothat when the replay mode of reproducing only the first recording layer4 occurs to read out the audio data recorded on the second recordinglayer 6. The audio data so read out are converted into analog audiosignals which are output at the output terminal 41.

If a replay mode selection button, not shown, provided on thereproducing apparatus 30, is acted on by the user, so that the replaymode of multiplexing and reproducing audio data recorded on the firstand second recording layers 4, 6 of the optical disc 1 is selected, theaudio data is reproduced by the following sequence of operations: Thatis, if the replay mode for multiplexing reproduction is selected, theCPU 37 decides to multiplex and reproduce the audio data read out fromthe first and second recording layers 4, 6 of the optical disc 1. If thereplay mode of multiplexing and reproducing the audio data is decided,the optical pickup 31 is switchingly controlled, by the servo circuit 38and the switching unit 39, to focus the replay light beam on one of thefirst and second recording layers 4, 6. The focussing point switchingtiming to the first or second recording layer 4, 6 is selected so that,in reproducing audio data recorded on the second recording layer 6 afterreproducing audio data recorded on the first recording layer 4, thesecond recording layer 6 commences to be reproduced at a time pointprevious to the replay end time point of the audio data of the firstrecording layer 4 on the time axis, and so that reproduction iscontinued up to a time point posterior to the reproduction end timepoint of audio data on the first recording layer 4, with thereproduction being then shifted to a focussed position of the light beamon the first recording layer 4. That is, referring to FIG. 6A, ifreproduction is made from a point P₁₁ on the first recording layer 4 upto a point P₁₂ on the first recording layer 4 and subsequently thereproduction is to be shifted to the second recording layer 6, thefocussing point of the light beam reverts to a point temporally previousto the replay end time point P₁₂ on the first recording layer 4 toinitiate the reproduction of the second recording layer 6 as from thetime point P₂₁, the second recording layer 6 is reproduced as from thereplay end time point P₁₂ on the first recording layer 4 up to atemporally posterior point P₂₂, and reproduction is initiated with thefocussing point of the light beam on the point P₁₂ on the firstrecording layer 4. Reproduction as from the point P₁₂ on the firstrecording layer 4 continues up to a point P₁₃ temporally posterior tothe replay end time point P₂₂ on the second recording layer 6. Ifreproduction is to be transferred to the second recording layer 6, thefocussing point of the light beam is caused to revert to the replay endtime point P₂₂ of the second recording layer 6 so that the secondrecording layer 6 is reproduced up to a time point P₂₃ temporallyposterior to the replay end point P₁₃ of the first recording layer 4.Meanwhile, the focussing point of the light beam is switched by movingthe light beam focussing point along the optical axis of the objectivelens 11 of the optical pickup 31, that is along the focussing direction.

The audio data read out at the replay timing shown in FIG. 6A from thefirst and second recording layers 4, 6 at the replay timing shown inFIG. 6A are routed to the signal readout unit 32 so as to be reproducedin accordance with the above-mentioned timing as described above. Inoutputting readout signals read out from the first or second recordinglayers 4, 6, the signal readout unit 32 outputs to the CPU 37discrimination data indicating whether the data pre-recorded on thefirst and second recording layers 4, 6 and read out therefrom is to besummed or subtracted. The CPU 37 controls the write or readout timing toor from the first and second buffer memories 33, 34 via buffermanagement unit 36.

The data write timing to the first or second buffer memories 33, 34 isanalogous to the replay timing shown in FIG. 6A or readout timing in thesignal readout unit 32. On the other hand, data readout timing from thefirst or second buffer memories 33, 34 is set so that data readout willbe initiated after storage of a pre-set quantity of data written in thefirst and second buffer memories 33, 34. Theoretically, data is read outfrom the optical disc 1 at a high readout speed not less than twice theprescribed standard readout speed and written at the aforementionedtiming in the first and second buffer memories 33, 34. The audio datarecorded on the first or second recording layers 4, 6 are read out andreproduced. After a pre-set amount of data has been written in the firstor second buffer memories 33, 34, output data corresponding to the audiodata recorded on the second or first recording layers 6, 4 is read outfrom the first buffer memory 33 or from the second buffer memory 34 soas to be multiplexed by the multiplexer 35. For non-interruptedreproduction from the first or second recording layer 4, 6, at least thedouble speed is required, as described above, if the switching time inswitching the replay timing of the first and second recording layers 4,6, is also taken into account. In actuality, the spindle motor 40 is runin rotation at a speed not less than the quadrupled speed so that theoptical pickup 31 will read out the data recorded on the optical disc athigh read-out rate.

The changeover timing in illuminating the first or second recordinglayers 4, 6 as the focussing position of the playback light beamradiated from the optical pickup 31 is switched between the recordinglayers 4 and 6 may be such a timing as is shown in FIG. 6B. The firstrecording layer 4 is reproduced as from the time point P₁₁ up to thetime point P₁₂ in the first recording layer 4. When reproduction is tobe shifted to the second recording layer 6, the second recording layer 6commences to be reproduced as the scanning point by the light beamreverts to the time point P₂₁ temporally previous to the replay endpoint P₁₂ of the first recording layer 4 up to the point P₂₂ of the sametiming as the replay end point P₁₂ of the first recording layer 4. Thelight beam focussing position then is shifted to the first recordinglayer 4 to initiate the reproduction of the first recording layer 4 asfrom the point P₁₂ of the first recording layer 4. The reproduction asfrom the point P₁₂ of the first recording layer 4 continues to a pointP₁₃ temporally posterior to the replay end point P₂₂ of the secondrecording layer 6. When reproduction is to be shifted to the secondrecording layer 6, the light beam scanning position is caused to revertto the replay end point P₂₂ on the second recording layer 6 to reproducethe second recording layer 6 up to the point P₂₃ of the same timing asthe replay end point P₁₃ of the first recording layer 4.

The signal read out from the first and second recording layers 4, 6 inthe reproduction timing shown in FIG. 6B is routed to the signal readoutunit 32 so that the replay signal processing is carried out inaccordance with the above-mentioned timing as described above.

FIG. 6C shows the changeover timing of a five-layered optical disc,having five recording layers, as a recording medium, as anotherembodiment of an optical disc having plural recording layers.Specifically, FIG. 6C shows the changeover timing in sequentiallyswitching from one recording layer to another, using a sole opticalpickup, in reproducing the audio data recorded in each recording layerof the optical disc.

In switching the focussing position of the replay light beam, radiatedfrom the optical pickup, from the first recording layer to the secondrecording layer, from the second recording layer to the third recordinglayer, from the third recording layer to the fourth recording layer andfrom the fourth recording layer to the fifth recording layer,reproduction reverts to points temporally previous to the replay endtime points P₁₂, P₂₂, P₃₂ and P₄₂ of the previously reproduced layer,respectively. As for the replay timing of the second, third and fourthrecording layers, these layers are reproduced up to the points P₂₂, P₃₂and P₄₂ of the same timing as the replay end points P₁₂, P₂₂, P₃₂ of thetemporally previous recording layer. However, the replay timing of thefifth recording layer is such that the fifth recording layer isreproduced up to a replay end time point P₅₂ which is temporallyposterior to the replay end time point P₄₂ of the fourth recordinglayer.

In the reproduction apparatus 30, shown in FIG. 5, it is possible torealize variegated reproduction, such as reproduction of datasynthesized from data of a lyric and data of the accompaniment music forthe lyric, making up with the lyric the complete musical number recordedon the first or second recording layers 4, 6 of the optical disc 1, orreproduction of data corresponding to the entire musical number recordedon one of the first and second recording layers 4, 6 less data of thelyric or the accompaniment music of the lyric of the musical numberrecorded on the other recording layer. In the first and second recordinglayers 4, 6, data of the lyric and data of the accompaniment music of acomplete musical number are recorded, so that audible musical numberreproduction is possible irrespective of on which recording layer theaudio data reproduced have been recorded.

An embodiment of the recording apparatus for recording audio signals onthe first or second recording layers 4, 6 of the optical disc 1 at apre-stage to the sampling stage by an LPF is hereinafter explained.

Referring to FIG. 7, the recording apparatus 45 includes a first inputterminal 46, fed with audio signals recorded on the first recordinglayer 4 of the optical disc 1, and a second input terminal 146, fed withthe audio signals recorded on the second recording layer 6.

It is noted that the first input terminal 46 is fed from a sound source,not shown, with entire audio signals of a complete musical numbercomprised of a lyric and the accompaniment music for the lyric, aspartial audio data, and, the second input terminal 146 is fed with asound source, not shown, with audio signals of an accompaniment musicportion of the complete musical number containing the lyric portion andthe accompaniment music of the lyric portion.

Alternatively, the first input terminal 46 may be fed from a soundsource, not shown, with entire audio signals of a complete musicalnumber comprised of a lyric and the accompaniment music for the lyric,as partial audio data, and a second input terminal 146 is fed with asound source, not shown, with audio signals of lyric portion of thecomplete musical number containing the lyric portion and theaccompaniment music of the lyric portion.

Still alternatively, the first input terminal 46 may be fed from a soundsource, not shown, with audio signals of an accompaniment music for alyric of a complete musical number comprised of the lyric and theaccompaniment music for the lyric, as partial audio data, and the secondinput terminal 146 may be fed with audio signals of lyric portion of thecomplete musical number containing the lyric portion and theaccompaniment music of the lyric portion, as partial audio data.

It is noted that the audio signals fed to the first and second inputterminals 46, 146 are stereo audio signals of two channels, namely leftand right channels, enabling the stereophonic reproduction.

The audio signals, fed to the first and second input terminals 46, 146,are processed with sampling with the sampling frequency of 44.1 kHz and16-bit quantization, for each of the left and right channels, forrecording on the first and second recording layers 4, 6.

The first audio signals, input to the first input terminal 46, areamplified by a first line amplifier 47, and then supplied to a firstadder 49 adapted for adding dithering to the signals. The dithering is arandom noise of small amplitude supplied from a dither generator 48.From the first audio signal, added to with the dithering by the firstadder 49, signal components of a frequency range not higher than 20 kHzare taken out by a first low-pass filter (LPF) 50 and thence routed to afirst sampling circuit 51. This first sampling circuit 51 appliessampling at a sampling frequency of 44.1 kHz to a filtered output of thefirst LPF 50. This sampling data is converted into 16-bit digitalsignals by a first A/D converter 52.

The second audio signals, input to the second input terminal 146, areamplified by a second line amplifier 147, and thence supplied to asecond adder 149 adapted for adding dithering to the signals. Thedithering is a random noise of small amplitude supplied from the dithergenerator 48. From the second audio signal, added to with the ditheringby the second adder 149, signal components of a frequency range nothigher than 20 kHz are taken out by a second low-pass filter (LPF) 50and thence routed to a second sampling circuit 151. This second samplingcircuit 151 applies sampling at a sampling frequency of 44.1 kHz to afiltered output of the second LPF 150. This sampling data is convertedinto 16-bit digital signals by a second A/D converter 152.

The first digital audio signals, derived from the first audio signalsoutput from the first A/D converter 52, are stored in a first buffermemory 53. The first digital audio signals, read out from the firstbuffer memory 53, are routed to a first error correction coding circuit54 so as to be processed with cross interleaving employing the CIRCalgorithm combined with four-order Reed Solomon code. The encoded dataoutput from the first error correction coding circuit 54 isEFM-modulated by a first modulation circuit 55 so as to be processed forrecording on a first recording circuit 56 and so as to be recorded onthe first recording layer 4 of the optical disc 1 by one of two opticalpickups shown in FIG. 2.

On the other hand, the second digital audio signals, derived from thesecond audio signals, output from a second A/D converter 152, are storedin a second buffer memory 153. The second digital audio signals, readout from the second buffer memory 153, are routed to a second errorcorrection coding circuit 154 so as to be encoded by the crossinterleaving employing the CIRC algorithm combined with four-order ReedSolomon code. The encoded data output from the second error correctioncoding circuit 154 is EFM-modulated by a second modulation circuit 155so as to be processed for recording on a second recording circuit 156and so as to be recorded on the second recording layer 6 of the opticaldisc 1 by the other optical pickup shown in FIG. 2.

In the optical disc 1 of each of the above-described embodiments, pluralrecording layers are provided in superposition and the entire musicalnumber or a portion thereof is recorded in each recording layer aspartial audio data. It is however possible to split the major surface ofan optical disc 60 into two or more plane portions on which to recordthe entire musical number or its partial portion.

In an inner peripheral portion of the optical disc 60 shown in FIG. 8,there is provided a first recording region 62, on an outer peripheralside of which there is recorded a second recording region 65.

In the first recording region 62, the entire audio signals of a completemusical number comprised of the lyric and the accompaniment music arerecorded as partial audio signals. In the second recording region 65,the audio signals of the accompaniment music of the complete musicalnumber comprised of the lyric and the accompaniment music are similarlyrecorded as partial audio signals.

Alternatively, the audio signals of the accompaniment music of acomplete musical number comprised of the lyric and the accompanimentmusic may be recorded as partial audio signals, and the audio signals ofthe lyric of a complete musical number comprised of the lyric and theaccompaniment music may be recorded as partial audio signals.

The first and second audio signals, recorded on the first and secondrecording regions 62, 65, are converted into digital audio signals fromsampling data generated on sampling with the sampling frequency of 44.1kHz followed by 16-bit quantization, so as to be processed with errorcorrection processing and EFM modulation as in the above-describedembodiment for recording in the respective recording regions 62, 65, asin the embodiment described above.

Adjacent to the inner rim of the first recording region 62, there isprovided a first management area 61 for supervising the audio datarecorded on the first recording region 62. Adjacent to the inner rimside of the second recording region 65 and to the outer rim side of thefirst recording region, there is provided a second management area 64for supervising the audio data recorded in the second recording region65. In the first management area 61, there are recorded firstdiscrimination data for indicating the presence of the second recordingregion 65 and second discrimination data indicating whether the datarecorded in the first recording region 62 and data recorded in thesecond recording region 65 are to be multiplexed and reproduced.

The optical disc 60 has a center opening 67. The first management area61, the first recording region 62 and a first read-out area associatedwith these regions 61, 62 form a first session 68, and the secondmanagement area 64, the second recording region 65 and a second read-outarea associated with these regions 64, 65 form a second session 69.

The audio data recorded on these recording regions 62, 65 are recordedsuch as to be reproduced by a routine reproducing apparatus for acompact disc employing a light beam of 780 nm. The accompaniment musicportion or the lyric portion of a complete musical number, comprised ofthe accompaniment music portion and the lyric portion, are recorded as aset, as in the case of the above-described optical disc 1, so that, ifthe audio data recorded in the recording regions 62, 65 are reproducedindependently of each other, the audio data so reproduced can be heardas the music number.

The recording medium according to the present invention may be anoptical card or a semiconductor memory, in addition to an optical disc.

INDUSTRIAL APPLICABILITY

If a recording medium according to the present invention is reproduced,a musical number composed of the lyric and the accompaniment music orthe orchestra performed by plural sorts of musical instruments can bereproduced as a set of audio signals. Moreover, only the accompanimentmusic portion of a musical number composed of the lyric and theaccompaniment music, or the performance by only certain musicalinstrument(s) of the orchestras, may be reproduced, so that the user isable to selectively hear a desired one of variegated audio reproduction.

1. A reproducing apparatus for reproducing audio signals from a recording medium on which sampled data generated by sampling audio signals from a sound source at a predetermined sampling frequency are recorded in a plurality of recording regions as said sampled data are separated into a plurality of partial portions including said audio signals in their entirety, said reproducing apparatus comprising: readout means for reading signals from said plurality of recording regions of said recording medium; and control means for controlling whether signals on each of said plurality of recording regions read by said readout means are to be reproduced individually or signals of a plurality of said regions are to be synthesized and reproduced, wherein when said recording medium is a disc shaped recording medium having two recording layers, said control means uses said readout means to reproduce a first layer, said control means in reproducing a second layer shifts to a point temporally previous to a replay end time point of said first layer to initiate reproduction, and said control means shifts after reproduction of said second layer to a point temporally posterior to said replay end time point to shift reproduction to said first layer.
 2. The reproducing apparatus according to claim 1, wherein said readout means reads said signals from each of said plurality of recording regions and said control means synthesizes data obtained from each of said plurality of recording regions to reproduce said synthesized data.
 3. The reproducing apparatus according to claim 2, wherein said readout means includes a plurality of readout mechanisms.
 4. The reproducing apparatus according to claim 2, wherein n represents a number of said recording regions, said readout means uses a single readout mechanism for reading said plurality of recording regions, and said control means causes said readout means to read said plurality of recording regions at a rate not less than n times a rate required by audio signals recorded in said respective regions to buffer said read audio signals to output said buffered signals when a volume of said buffered signals reaches a predetermined volume.
 5. A reproducing method for reproducing audio signals from a recording medium on which sampled data generated by sampling audio signals from a sound source at a predetermined sampling frequency are recorded in a plurality of recording regions as said sampled data are separated into a plurality of partial portions including said audio signals in their entirety, said reproducing method comprising the steps of: reading signals from said plurality of recording regions of said recording medium; and controlling whether signals of each of said plurality of recording regions of said recording medium read are to be reproduced individually or signals recorded in at least two of said plurality of regions are to be synthesized and reproduced, wherein when said recording medium is a disc shaped recording medium having two recording layers, said step of reading reproduces signals from a first layer and said step of controlling controls reproducing a second layer and shifts to a point temporally previous to a replay end time point of said first layer to initiate reproduction of said second layer, and after reproduction of said second layer said step of controlling shifts to a point temporally posterior to said replay end time point to shift reproduction to said first layer. 